Photodetection device and photodetection system

A photodetection system, comprising:

• a light-emitting section that emits light;
• and
• a photodetector that detects light reflected by a detection object of the light emitted from the light-emitting section, wherein
• the photodetector includes
• a plurality of light-receiving sections that each includes a light-receiving element, and generates a first pulse signal including a pulse corresponding to a result of light reception by the light-receiving element,
• an adder that generates a second pulse signal by selecting one or more first pulse signals from a plurality of first pulse signals generated by the plurality of light-receiving sections and performing addition processing on a basis of the one or more selected first pulse signals,
• a divider that performs division processing for dividing the second pulse signal into a plurality of third pulse signals in a time division manner on a basis of a clock signal,
• a plurality of counters that is provided corresponding to the plurality of third pulse signals, and each performs count processing on a basis of a corresponding one of the third pulse signals, and
• a controller that sets a signal number of the one or more first pulse signals to be subjected to the addition processing on a basis of respective count values of the plurality of counters.